from the July 14, 2013 Newsletter issued
from the Frio Canyon Nature
Education Center in the valley of the Dry Frio River in northern Uvalde County,
southwestern Texas, on the southern border of the Edwards Plateau, USABLADDERWORTS
Last November we profiled a carnivorous plant, a bladderwort, found along the Dry Frio
River {discussed below}.. I couldn't identify those plants to species level. This week I
found another much larger population of bladderworts, and now I'm more comfortable
suggesting a species name, though I'm still not 100% sure. Above you can see a small part
of the community, their yellow flowers atop slender, leafless stems, or peduncles,
emerging from shallow water.

A flower close-up showing a yellow "spur" jutting
horizontally beneath the corolla's lower petal -- that petal bearing two bulges on its
surface -- is seen below:

That picture shows the spur tip reaching the outer rim of the lower petal but not
passing beyond it. Spurs on the bladderwort flowers found last November extended well
beyond the lower petal's outer rim, and that was one feature that confused me.

Bladderworts entrap microscopic aquatic animals in their underwater bladders, where the
animals are digested. You can see the bladders photographed last November in the next
section. The network of forking and reforking, submerged, bladder-bearing stems of this
week's population was extensive, as you can see below:

Probably this is UTRICULARIA GIBBA, sometimes called the Humped or Floating
Bladderwort. It's the most widespread of all bladderwort species -- all species of the
genus Utricularia -- and is found on all continents except Antarctica. It's the
only species listed for Uvalde County.

Last November I felt that those plants' long spurs poking from beneath the lower flower
petals disqualified them from being this species, but now I've learned that Utricularia
gibba varies a great deal across the world, including having flowers with especially
long spurs.

Something new is that earlier this year the genome of Utricularia gibba was
sequenced. One interesting tidbit of information resulting from that exercise is that now
we know that the ancestors of bladderworts split from the ancestors of tomatoes 87 million
years ago...

Utricularia gibba is considered to be easily grown in home aquaria -- even
small cups or bowls. In fact, I placed a small stem segment from the bladderworts found
last November in a jar of water, and now that jar is thick with bladder-bearing
bladderwort stems.

from the November 4, 2012 Newsletter issued from the
valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the
southern border of the Edwards Plateau, USABLADDERWORTS
Along the little Dry Frio River behind the cabin in a shallow, muddy pool where someone
has scooped out sand and gravel with a front-end loader, several fingernail-size, yellow,
snapdragon-like flowers rise about 1½ inches (4cm) from the water on slender, leafless
stems, as shown above.

The flowers are bilaterally symmetrical, but with curiously raised, tonsil-like bulges
in the throat, as shown below:

From above the population you can see that submerged in the water surrounding the
flowers there's an extensive, much-branched system of leaves and stems as shown below:

If you pick some of the submerged parts from the water you see that the strands bear
large numbers of bladderlike items averaging maybe 3/16ths inch across (2mm), as shown
below:

This is a wonderful, carnivorous aquatic called a bladderwort, genus Utricularia.
I can't figure out which species it is. It seems to be closest to UTRICULARIA FOLIOSA,
though it could be U. subulata. Both species are very widely distributed though
seldom common, and certainly rare in Texas. So, this is a good find and it worries me that
it's in a place where people dig gravel when they need it. I suppose the population became
established there when a bird such as a sandpiper stopped at the pool and a bladderwort
seed came loose from its body.

The bladderlike things in the last photo are traps for microscopic aquatic
invertebrates. They aren't used for floating. They are equipped with touch-sensitive
hairs, called trigger hairs, that when disturbed cause the bladders to quickly suck in
water along with whatever creature set off the trap. Digestive enzymes and bacteria in the
bladder then digest the prey for the nutritional use of the plant, a process typically
taking 15 minutes to 2 hours, depending on how large the prey was.

from the January 19, 2014 Newsletter issued from the
valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the
southern border of the Edwards Plateau, USABLADDERWORT BLADDERS
Here in winter the bladderworts aren't flowering but sometimes you find tangles of their
green, threadlike stems gathered here and there, as shown below in water half a finger
deep:

How can we be sure that this isn't just a filamentous alga? One way is to lift a thread
from the water and see if it bears bladders, as shown below:

In that picture, notice the branched hairs issuing from the blackish bladder in the
center. When in water and a microscopic aquatic animal brushes against one of those
"trigger hairs," a kind of trapdoor suddenly opens in the bladder. Before the
trapdoor opens, the bladder is not completely full of water so when it does open water
bearing the prey is sucked inside and the door closes. The whole process takes only ten to
fifteen thousandths of a second.

As we've seen with their yellow, snapdragon-like flowers, bladderworts are flowering
plants. However, bladderworts are so highly specialized -- for one thing, their vegetative
parts are not clearly separated into roots, leaves and stems -- that they have their own
family, the Bladderwort Family, or Lentibulariaceae. Their bladder traps are regarded as
one of the most sophisticated structures in the entire Plant Kingdom.